Method of obtaining uric acid from natural products

ABSTRACT

1. THE METHOD OF OBTAINING URIC ACID FROM A WASTE MATERIAL CONTAINING URIC ACID COMPRISING THE STEPS OF: COLLECTING SUITABLE URIC ACID BEARING WASTE MATERIAL PROMPTLY AFTER IT HAS BEEN PRODUCED; DRYING SAID PROMPTLY COLLECTED WASTE MATERIAL WITHIN A PERIOD OF EIGHT DAYS AFTER IT HAS BEEN PRODUCED AT A TEMPERATURE OF FROM BETWEEN 140*F. TO 390*F. FOR A PERIOD OF TIME UNTIL THE MOISTURE CONTENT IS REDUCED TO NO MORE THAN 15% WEIGHT OF WATER; MILLING AND COLLECTING A FRACTION OF AT LEAST -80 MESH OF THE MILLED AND DRIED WASTE MATERIAL; EXTRACTING SAID FRACTION MATERIAL A FIRST TIME WITH AN ALKALINE-BRINE SOLUTION HAVING A PH OF GREATER THAN 9; ACIDIFYING THE MOTHER LIQUOR OF SAID FIRST EXTRACTED MATERIAL WITH AN ACID IN A SOLUTION HAVING A PH OF FROM 1 TO 5.5; EXTRACTING THE PRECIPITATED MATERIAL FROM THE ACIDIFIED SOLUTION A SECOND TIME BY DISSOLVING SAID PRECIPITATE IN AN ALKALINE-BRINE SOLUTION HAVING A PH OF GREATER THE 9; AND ACIDIFYING SAID SECOND EXTRACTED MATERIAL TO A PH OF FROM 1 TO 5.5 THEREBY PRECIPITATING THE PURE URIC ACID SO PRODUCED FROM THE SUPERNATANT LIQUID.

Nov. 26, 1974 J. D. DOUROS, .IR.. ET L 35 15 METHOD OF OBTAINING URICACID FROM NATURAL PRODUCTS Filed on. 7, 1970 NATURAL wASTE COLLECTWITHIN PROMPTLY DRY AND PRODUCT (89., mm 8 DAYS Tb I ILL MICROOCANISMSMANURE) TO STABILIZE URIC ACID EXTRACT wITH COLLECT FINER CRIND ANDSEIvE SODIUM HYDROXIDE Q FRACTION (e.g., 80 I SODIUM CHLORIDE MESH)CONTAINING SOLUTION (pH IO) MAJOR PORTION OF I I URIC ACID I II DISCARDINSOLUBLE ANIMAL FEED MATERIAL SUPPLEMENT SUPERNATANT CONTACT WITHACIDIFY wITH SUL- I; LIOUID CALCIUM CHLORIDE FURIC ACID (pH OF I" 'TOSETTLE OUT TO 6) TO PRECIPI- r LICNINS TATE URIC ACID I II I II DISCARDDISCARD LIQUID FLOCCULANT PASS SUPERNATANT HEAT SUPERNATANT EXTRACTPRECIPI- LIOUID THROUGH LIOUID FROM 70F TATE SODI M .HYROx-;I ACTIVATEDCARBON TO 2IOF IDE-SODIUM CHLOR- COLUNIN IDE SOLUTION I H IOI ACIDIFYwITH SUL- WASH URIC ACID ASH URIC ACID FURIC ACID (pH OFI INITH WATERWITH METHANOL TO 6) TO PRECIPI- TATE URIC ACID FLOWINS URIC ACID C APREFERRED METHOD OF OBTAINING PURE URIC ACID AND ANIMAL FEED SUPPLE-INVENTQQS JOHN D. DOUROS JR. MENT FROM WASTE MATERIAL IRA T WAR ER ig BYI ATTCDFQNEY United States Patent 3,850,930 METHOD OF OBTAINING URICACID FROM NATURAL PRODUCTS John D. Douros, Jr., Littleton, and Ira T.Warder, Jr.,

Lakewood, Colo., assignors to The Gates Rubber Company, Denver, Colo.

Filed Oct. 7, 1970, Ser. No. 80,517 Int. Cl. (107d 57/60 U.S. Cl.260-255 31 Claims ABSTRACT OF THE DISCLOSURE This invention relates toimprovements and methods of beneficiation of uric acid and primary saltsof uric acid. The compounds are obtained by treating fowl excrement orwaste material by means of first promptly collecting the waste material;removing the moisture therefrom, and then subsequently grinding andfractionating this material according to particle size. The methodresults in fractions of the original waste material which have increasedconcentrations of uric acid. The enrichment in uric acid concentrationresults in a material which is very suitable for final removal andtreatment of the contained uric acid. A process for the extraction ofhigh purity uric acid and primary salts of uric acid from the pretreatedwaste is also disclosed. The invention includes the utilization of thedrying and sieving process of the waste material to obtain portions fromthe original product which is suitable for animal feed and supplements.

BACKGROUND OF THE INVENTION It has been known that certain animal,reptile and fowl excrement contain various nitrogenous materials, asignificant portion of which may be found as uric acid. Uric acid hasthe empirical formula C H N O The structural formula is:

A major source of uric acid in the past has been marine bird guanoobtained primarily in the Galapagos Islands. A process has beendescribed in United States Letters Patent Number 2,302,204 for obtaininguric acid from bird guano. The process described therein involvesnumerous dissolution and precipitation steps, many of which are carriedout at elevated temperatures in a highly alkaline media which is knownto degrade uric acid. The complexity of this process, as well as theproduct loss which is caused by conditions under which it is carriedout, leave much room for improvement. On the other hand, improvementsdescribed herein disclose steps in which the raw material is promptlycollected, dried, ground and sieved. These preliminary steps constitutean improvement which involves very few steps but yet results in thebeneficiation of a very pure, high concentration or product in very highyields.

Disadvantages in the prior art overcome by the practice of the novelprocess of the present invention, which yields a substantially pure orpure (chemical and pharmaceutical grade) uric acid (in extremely highyields) which is characterized by exhibiting an improved color, i.e., isessentially colorless or white, has an extremely low concentration ofimpurities, and is prepared in a convenient, economical and eflicientmanner. In accordance, then, with the present invention, it has beenfound possible to pre- 3,850,930 Patented Nov. 26, 1974 pare pure(chemical and pharmaceutical grade) uric acid, in very high yields,having the aforementioned characteristics, which has heretofore not beenobtainable by prior art processes on a large scale. Additionally, theprocess as described herein is adaptable to obtaining substantially pureprimary salts of uric acid having the empirical formula of MHC H N O inwhich 'M is an alkali earth metal.

Uric acid is known in the art to have a significant value as a chemicalcompound and consequently, has a wide variety of uses. Uric acid, forexample, can be used for the commercial production of allantoin,alloxan, alloxantin, parabanic acid, murexide and other derivatives.Uric acid and its salts, for example, have been and are still being usedon occasion in medicine. It has been used internally for edematousheart, pulmonary tuberculosis, persecution mania, et cetera, and alsoexternally in gout. A 4% ointment of ammonium urate has been used in thetreatment of chronic eczema and also internally for coughs and grippe.Lithium acid urate is used as an antarthritic, and murexide is used asan organic indicator for the determination of calcium and other metalions.

The beneficiation method disclosed herein is particularly adaptable toutilization of waste material obtained from large commercial birdestablishments such as turkey and chicken far-ms. Thus, in addition toproviding a method for obtaining a valuable raw material such as uricacid and its primary salts, the process provides a solution for seriousdisposal problems and for obtaining a valuable animal feed andsupplement.

SUMMARY OF THE INVENTION This invention relates to utilization ofmechanical steps of treatment of fowl waste material or excrement forobtaining either uric acid, primary salts of uric acid or a material foruse as feed and supplement. The invention relates to a novel process formodifying fowl waste material by prompt collection of the material afterits production, generally within a 48-hour period. Prompt collection andtreatment of the waste material minimizes the microbial degradation ofthe naturally occurring uric acid. The prevention of the microbialdegradation also minimizes accumulation of metabolic by-products.

The raw material containing uric acid is then dried for a suflicientperiod of time and at a sufficient temperature to substantiallyterminate biological degradation thereof, to form a raw material whichhas a substantially stabilized uric acid content. Next, the stabilizeduric acid containing raw material is ground, sieved and separated intotwo separate fractions, a first fraction constituting said raw materialcharacterized by having a major portion of the stabilized uric acid anda second fraction constituting said raw material characterized by havinga minor portion of said stabilized uric acid. The first fraction isreacted with a sufficient amount of an aqueous alkaline-brine solution,which is capable of dissolving substantially all of the stabilized uricacid in the concentrated fraction, to form a uric acid solutioncontaining insoluble impurities. The insoluble impurities are removedfrom the solution of dissolved uric acid. A sutficient amount of aflocculating agent is mixed With the uric acid solution to form a slurrycontaining other insoluble impurities. The additional other insolubleimpurities are removed from the slurry to form a purer uric acidsolution. The second solution is reacted with a sufficient amount of anacidic material to form a uric precipitate. The precipitate is thenextracted with a sufficient amount of an alkaline aqueous solution todissolve substantially all the uric precipitate to form a third uricsolution. The third fluid is reacted with a sufficient amount of anacidic material to form a precipitate in the third fluid and which issubstantially pure uric acid.

At this point, the pure or substantially pure uric acid precipitate canbe separated and used as such or, if it is desired to store them or shipto a customer, the solution with the precipitated uric may then betreated to remove the bulk of the third fluid, washed and subsequentlydried.

It is, therefore, an object of this invention to obtain extremely pureuric acid from normally waste material.

It is a further object of this invention to provide mechanical means forbeneficiation of uric acid and other useful nitrogenous materials innormally waste products.

It is another object of this invention to provide novel processes forthe manufacture and production of substantially pure uric acid fromnatural sources such as chicken manure.

It is a further object of the present invention to provide novelprocesses for producing purified uric acid substantially free ofcolor-producing bodies and/ or other impurities.

It is another object of this invention to provide an economical methodof producing a low cost feed and supplement, from normally wastematerial.

TECHNICAL DISCLOSURE A uric acid bearing raw material is utilized as thestarting material in the processes in this part of the presentinvention. The term waste material, as used herein, designates and meansexcrement of any reptiles, birds and fowl which contains uric acid. Suchwaste material is collected and dried generally within a seven-dayperiod, preferably a 48-hour period, and most preferably a 24-hourperiod, from the time that the excrement is produced.

Birds or fowl such as chickens and turkeys are known to excrete materialcontaining uric acid; however, the content previously reported isrelatively low, e.g., 2 t 3% by weight. One of the unique facets of thepresent invention, however, relates to the fact that substantiallyhigher uric acid containing raw materials can be obtained. It has beenfound that aging of fowl or reptile excrement or waste material will domuch to decrease the amount of naturally occurring uric acid occurringin the waste material because of microbial attack. With moisture contentin excess of 10% rapid microbial attack can be maintained on thenaturally occurring uric acid itself since it can serve as the solesource of carbon and nitrogen necessary for microbe existence. Dataindicates that material collected and processed within a 24- hour periodwill show a 6 to 8% higher yield than that previously reported in theliterature. Thus, fresh chicken waste will actually contain as high asto 12% uric acid. The yield may drop to as low as 1.5% uric acid at theend of a 24-hour period and as low as 0.7% in 48 hours. Material that is120 hours old will generally show less than 0.1% of uric acid but mayshow as little as 0.07%. Finally, material that is 8 days old willinvariably show less than 0.05% or only negligible amounts. One of theinventive portions of this process, therefore, is the prompt collectionof fresh material and processing of the waste material to obtain optimumyield of uric acid. The recommended limit is to make collections withina 48-hour period of time, but the most preferred method is to makecollections daily.

It has also been observed that uric acid varies in the waste product dueto the diet, age and health of the chickens. The consistency of the wetand the dry waste material also changes according to the diet of thechickens. If the diet consists mainly of fish meal, the uric acid andlysine content of the waste material increases. On the other hand, ifsoy is fed, the waste material is much more fibrous. Some illustrationsof the effect of diet on the uric acid content of the dried waste isshown in Table I.

TABLE I.URIC ACID CONTENT OF SPECIFIC SIEVED FRACTIONS OF CHICKEN WASTEFROM TWO DIFFERENT DIET SOURCES Urie acid concentration, percent byweight of Mesh size dried waste Cotton seed and fish Greater than 1.15meal. 50 to 80 mesh 1.11 80 to 120 mesh... 0. 25

120 to 170 mesh... 0.32

170 to 200 mesh... 0.

200 to 270 mesh 4. 35

Less than 270 mesh... 0.75

Total-.... 8.52

Soybean m aal diet with Greater than 50. 0. 82 high corn. 50 to 80 mesh0.72 80 to 120 mesh 0.78

120 to 170 mesh... 5.01

170 to 200 mesh-.. 1.

200 to 270 mesh 0 Less than 270 mesh..

Total Z 9. 03

l Purity 87%. Purity 74%.

After the prompt collection of the waste material, the next subsequentstep, therefore, is a drying process which will terminate decompositionor degradation due to microbial action. Such drying is desirable sincethe waste material ordinarily consists of from 70 to 80% water. A numberof drying methods are known in the art, most of which may be utilized.Drum driers, fluid bed driers and flash driers are the ones preferred inthis process. The flash drier or drum drier seems to 'be the moredesirable methods since oven drying tends to scorch the material. Ovendrying also tends to form clumps of the product. When such clumpingoccurs, higher temperatures must be used in order to assure completemicrobial kill. It has been found that complete kill of all microbes maybe obtained at 390 F. However, a high carbohydrate diet waste willcaramelize at a higher temperature. Reference to Table II shows thisrelationship. However, a drying range of 140 to 390 F. is quiteacceptable if the process is to be carried out for the extraction ofpure uric acid. The preferred procedure is to utilize a drying stepuntil the moisture has been reduced to 5 to 15% weight of water. Thedrying procedures not only allow one to work on a more concentratedmaterial, but it also minimizes handling and disease problems.

TABLE II Destruction of Microorganisms in Dried Fowl Waste as a Functionof Drying Temperature Organisms per gram Wet fowl waste 22x10 265 F.(Flash drying) 2x10 280 F. (Flash drying) 0.5 10 300 F. (-Flash drying)0.25 1O 350 F. (Flash drying) No organisms In addition to diet havingeffect on the uric acid content, it has also been found, and is aspecific embodiment of this invention that specific sievedfractionations of the dried waste material will tend to concentrate theuric acid in the smaller sieved fractions. The relation of uric acidcontent to specific sieve fractions is also illustrated in Table I.

Referring again to Table I, an interesting observation may be made. Itis obvious that higher uric acid concentration will be found in thesmaller mesh sizes. For instance, in the cotton seed and fish meal diet,almost 75% of the uric acid is found in the less than mesh sieve sizes.In the soybean meal diet, the result is even more dramatic with 83% ofthe uric acid found in the less than 80 mesh diet.

Thus, a very important part of this invention is a grind ing andseparation procedure for the material according to a proper particlesize classification. This is true regardless of the fact that it wasshown that the yield of uric acid will vary according to the diet of thefowl. Very great beneficiation of uric acid can be found by classifyingand obtaining the fraction of less than 80 mesh. Accordingly, afterdrying, the material is ground using commonly known methods such as ahammer mill, ball mill, or rod mill. The material is then sifted throughvarious screens of up to 325 mesh. It has been unexpectedly found anddiscovered in conjunction with the experimentation of the presentinvention, that if the dried raw material is milled to provide a productwhich has an average particle size diameter of less than 2,000 microns,preferably less than 1,000 microns, and then subjected to a sievingoperation on a screen which is no larger than a No. 20, and preferably aNo. 50 and most preferably a No. 80 mesh US. Standard screen, theresultant smaller sized fraction passing therethrough will contain amajor portion by weight of the uric acid, based on the total weight ofthe uric acid in the total dried raw material being sieved. By the sametoken, this minus 80 mesh fraction will constitute general- 1y only fromabout 50% by weight of the raw material, based on the total weight ofthe dried raw material being sieved, or 85% by weight of minus 50 meshfraction.

The concentration of uric acid in the 325 mesh particle size fraction ofthe dried fowl waste is illustrated by the fact that uric acid ofgreater than 75% purity can be obtained from the less than 325 meshmaterial using air classification. It is not necessary, however, toutilize such a small mesh concentration. For example, the less than 80mesh particle size fraction which constitutes from 30 to 40% of thetotal dry weight, contains from 70 to 85% of the total uric acidcontent. Generally speaking, there is no particular gain by utilizingthe smaller mesh fractions. Very little increased uric acid content isobtained by collectng 120 mesh rather than the 80 mesh fraction. On theother hand, the uric acid content and the fraction of 50 mesh or lessdrops to only to of the amount found in the finer fraction. It is,therefore, preferred to sieve the dry material and collect the less than80 mesh size material. It is thus seen that merely by utilizing thissingle important mechanical step a high beneficiation of uric acid canbe obtained.

Beneficiation of the uric acid content resulting from the grinding andseparation according to particle size is illustrated by the data inTable I. The grinding and sieving of dry fowl Waste produces materialswhich have feed and supplement value. A dried fowl waste sieved througha 120 mesh screen gives two fractions quite different in chemicalmake-up, thus, different in industrial value.

TABLE III.EFFECT OF PARTICLE SIZE ON ANALYSIS OF DRIED FOWL WASTE In thedata shown in Table III, the greater than 120 mesh fraction represented73% of the total dried waste, whereas the less than 120 mesh represented27% of the total dried waste. It is, thus, obvious that theconcentration according to particle size not only enriches orbeneficiates the material, but it cuts down drastically on the weightpercent of material which must be handled. The data in Table III isillustrative of the usefulness of this process in obtaining a productfrom fowl waste which has utility as an animal feed and supplement.Either fraction or the entire material is suitable for animal food use.This beneficiation and obtaining of feed and supplement is, therefore, apart of this invention.

A product can be obtained which functions as a nonprotein nitrogensupplement for use in animal feed and supplement and has other nutrient.value which is readily recognized by those who are familiar with animalnutrition. Uric acid itself has been found to be a good nonprotein,nitrogen source. The uric acid can serve as a non-protein, nitrogensource material which can be used for feed cattle, dairy cattle, rangecattle, swine and sheep. Because of the slow releasing properties ofuric acid, bloating is not a problem when this material is used as anonprotein, nitrogen source in the diet. In addition, this product hasan increased value due to its mineral concentration, carbohydrateconcentration and crude fat concentration. Uric acid would be a bettersource than urea for non-protein, nitrogen for use in ruminant animalssince uric acid releases less gaseous ammonia.

In general, this part of the invention provides a process for preparingan animal feed and supplement and which comprises the steps of: (I)promptly collecting a freshly produced uric acid containing wastematerial; (2) drying suitable raw material for a sufficient period oftime at a sufficient temperature to substantially completely terminatebiological degradation thereof, to form an animal feed and supplementwhich has a substantially completely stabilized uric acid content and;(3) milling the stabilized uric acid containing animal feed andsupplement to a suitable size for subsequent internal consumption bysaid animal.

The drying of the raw material is of importance to the process.Specifically, this drying step takes place at a temperature of at least350 F. It is found that at temperatures less than about 350 F. there isa possibility of microorganisms present which cause fermentation in theraw material, The fermented raw material, in turn, may be toxic toanimals. However, with the heating of the raw material, the resultingproduct is an excellent animal feed and supplement and growthstimulator.

The drying takes place for a period of time sufficient to reduce themoisture content of the raw material to less than about 10% by weight,based on the total weight of the wet raw material and preferably to amoisture content of from about 1% to about 9% by weight.

The dry raw material is then milled for a sufficient period of time,preferably to produce a product which has a particle size of less than2,000 microns. At this point the product can be utilized as such or themilled dry raw material may be formed for an animal feed and supplementfor subsequent internal consumption by the animal. It is to beunderstood that it is within the scope of the present invention to sievethe afore-described dry, milled, raw material and use the plus fractionas the animal feed and supplement and use the minus fraction for thepreparation of substantially pure uric acid. Such an operating techniquewould result in achieving the maximum benefit out of the dry, milled,raw material.

Even though the feed supplement itself contains nonprotein nitrogen,this material is capable of being converted by rumen microorganisms intoprotein material. Normally, such feed supplements, for instance, urea,are added at the rate of l to 2% to an average diet for cattle;Examination of Table III shows the nutrients obtainable, most of whichare found in commercially common feed supplements.

While uric acid per se has been found to be a good nonprotein, nitrogensource for ruminant animals (Pages 193- 202, Journal of Nutrition,Volume 94, R. R. Oltjen, et al., 1968), this novel animal feed andsupplement also has additional advantages such as its mineral,carbohydrate and crude fat concentrations which permit said supplementto be used as a substitute for other nutrients in an animal feedcomposition. Thus, it has been found that the present invention animalfeed and supplement can be used in an animal feed composition in amountsof up to at least by weight, based on the total weight of saidcomposition.

It is to be understood then that the animal feed and supplement of thepresent invention can be used with or as a complete replacement for anyof the usual nutritionally-balanced quantities of carbohydrates,proteins and c minerals. Some of these usual dietary elements aregrains, such as ground grain and grain by-products; animal proteinsubstances, such as those found in fish meal and meat scraps; vegetableprotein like soybean oil meat or peanut oil meat; and bone meal andlimestone.

EXAMPLE 1 Approximately 25,000 pounds of wet chicken manure which has awater content of 80% by weight based on the total weight of the wetmanure was collected within a 24- hour period of its production. The wetchicken manure was dried in a flash drier at a temperature ofapproximately 390 F. for a sufficient period in order to form a productwhich had a water content of approximately 5% by weight thereof. Thedried product weighs approximately 5,000 pounds. The 5,000 pounds ofdried chicken manure product was passed through a hammer mill and milledto form a product which had an average particle size diameter of about1,500 microns. This material was sieved using a No. 120 mesh US.Standard screen. The plus 120 mesh fraction of the raw materialrepresenting approximately 73% by weight of the total raw material, wasfound to have the following composition:

Ingredient: Percent by Weight Crude fats 2.4

Silicates 1.6 Carbohydrates 8.9 Phosphorus 2.0 Calcium 10.7 Magnesium0.4 Uric Acid 5.0 Nitrogen 4.6 Crude Fibers 11.8 Water 5 .0 Remainder(inorganic anions and other carbon,

hydrogen and oxygen moieties) 47.6

Eight Hereford steers averaging about 700 pounds in weight were dividedinto two groups of four steers each. The first or control group ofsteers and the second group of steers were fed the following animal feedcompositions:

The control group and second group of steers were respectively fed about20 pounds per day of the afore-described feed compositions over a130-day period. At the end of this 130-day period the control group hadan average weight of about 1,010 pounds while the second group which wasfed on the present invention feed composition had an average weight ofabout 1,100 pounds. Thus, the first group had 44.3% increase in weightas contrasted to 57.1% increase in weight which was experienced by thesecond group. No adverse effects were noted by feeding the second groupthe present invention feed composition. 75

8 EXAMPLE 2 A method for preparing ruminant feed supplement was utilizedto obtain nutrients according to the breakdown in Example 1. Chickenmanure was collected within 24 hours of its production and dried in aflash drier at 380 F. The dried material was passed through a ball milland sieved into a fraction of -120 mesh. The less than 120 mesh particlesize fraction represented 57% of the weight of the original driedchicken waste. The separated fractions gave substantially the sameanalysis as shown in Example 1. The product was tested and found tocontain no live organisms after the drying. The material was added atthe rate of 2% as a food supplement to a feed of 10% hay and 88% mile.

EXAMPLE 3 Example 1 was repeated again with the sole exception that themilled, dry, raw material is not sieved but used as such. Substantiallythe same results are achieved as found in Example 1.

It is quite apparent from the foregoing results that the presentinvention feed composition is suitable for feeding various animals.Either or both fractions or the total product is useful as feed.

If it is desired to use the waste product for obtaining uric acid in apure form, the material is then further treated. Methods according tothis invention have been devised for obtaining uric acid from thematerial by both continuous and batch processes. Generally, however, thetype of treatment is the same and will be disclosed in that manner whena specific example is given for either the batch or continuous process.

The methods described are equally applicable to a chemical treatment forpurification of the waste material for obtaining not only uric acid butmonosodium urate or at least a monosalt of uric acid.

The next step, heretofore set forth, is the reaction of the raw materialwhich passes through preferably an mesh screen or any fractioncontaining a majority of the uric acid, based on the total weight of theuric acid before the milling and screening, with a sufficient amount ofan aqueous alkaline solution in order to dissolve the uric acid andseparate it from the remaining matter in the raw material. This reactionbetween the uric acid enriched raw material and the aqueous alkalinesolution results in a slurry which contains insoluble material. It isfound by this reaction step that the uric acid which is in the form of asalt thereof is dissolved in the aqueous alkaline solution but that themajority of the remaining raw material is insoluble and consequently cansubsequently be removed.

It is to be understood that the term aqueous alkaline solution usedherein covers any aqueous solution containing any inorganic material ororganic material which will provide a pH of aqueous solution of at least6.5, preferably greater than pH 9, and most preferably greater than pH10. Furthermore, the inorganic or organic material is any alkalinematerial which will provide a cation which forms a salt with uric acidand consequently allows the uric acid to be substantially completelydissolved in the aqueous alkaline solution. The inorganic material canbe sodium, lithium, potassium and ammonium hydroxides, carbonates,bicarbonates, phosphates and nitrates. The organic material which can beutilized can be alkali metal acetates such as sodium acetate and alkalimetal citrates such as sodium citrate. It is also within the scope ofthe present invention that various amines which will provide the aminesalts of uric acid which are soluble in an aqueous alkaline solution canbe utilized. The water soluble amines such as low molecular weightamines, having a molecular weight below about 300, are preferred.Illustrative of such amines are the alkyl amines, alkylene amines andalkanol amines containing not more than 2 amine groups, such as ethylamine, diethyl amine, propyl amine, propylene amine, hexyl amine,2-ethyl hexyl amine, N-butyl ethanol amine, triethanol amine and thelike.

It is to be understood that mixtures of both the inorganic and organicmaterials can be utilized. Of the materials heretofore set forth, thesodium, lithium and potassium hydroxide materials are preferred; and thesodium hydroxide material is the most preferred material. It is alsowithin the scope of the present invention that a brine solution such assodium chloride can be utilized in order to enhance the solubility ofthe uric acid material.

The amount of alkaline material in water used in conjunction with theuric acid enriched raw material passing through the desired sieve, is atleast suflicient to adjust the aqueous alkaline solution to a pH of 6.5,preferably greater than 9, and most preferably greater than 10. Inconjunction with the experimentation with the processes of the presentinvention, it has been found that the alkaline material is usuallypresent in an amount of from about 2% to about 20% by weight, based onthe total weight of the uric acid enriched raw material passing throughthe desired sieve. However, any amount can be used as long as thespecific pH limitations described above are met.

In conjunction with the aqueous alkaline solution, the solvent thereinis preferably water. It is desirable to have a weight ratio of solventto raw material (being treated) of from about 5:1 to about 1,200:1 andpreferably from about :1 to about :1.

While this step in the novel processes of the present invention utilizeswater as the solvent in the aqueous alkaline solution as heretoforedefined, it is also within the scope of the present invention to utilizea non-aqueous alkaline solution, with the condition that the solventwhich contains the alkaline material is such that will permit the saltsof uric acid to be dissolved therein. For example, certain types ofalcohols, ketones and ethers would permit the substantially completedissolution of the uric acid salts therein.

In conjunction with the experiments carried out regarding the presentinvention, it was also discovered that, when the aqueous alkalinesolution contains an electrolyte therein, the combination of theelectrolyte and alkaline material results in a favorable increase in theyields of the uric acid. It is to be understood that any commonly knowntype of electrolyte can be utilized as long as there is no adverseeffect in conjunction with achieving the desired end-result. In general,the alkali metal, alkaline earth metal, halides, nitrates, hydroxides,sulfates and carbonates are to be considered as within the scope of thepresent invention. The preferred electrolyte for utilization in thepresent invention processes is sodium chloride. While some of theelectrolytes would also fall within the definition of the alkalinematerial used in conjunction with the aqueous alkaline solution, it isto be understood that the selection of the particular electrolyteutilized is predicated upon the use of a dilferent type of alkalinematerial. For example, where one utilizes an aqueous sodium hydroxidesolution as the dissolution medium for the uric acid, the electrolytewould not be an additional amount of sodium hydroxide but anothercompound such as sodium chloride.

The amount of electrolyte utilized will vary, depending upon, forexample, such factors as the temperature of the aqueous alkalinesolution, pH thereof and desired rate of dissolution of the uric acidtherein. However, it has been found during the experimentation of thepresent invention that the amount of electrolyte utilized is preferablyfrom about 0.01% to about 50% by weight based upon the total weight ofthe uric acid enriched raw material being dissolved in the aqueousalkaline solution. It is to be understood that any amount can beutilized, however, as long as the electrolyte is effective in achievingthe desired end result which is generally the increase in the yield ofthe pure uric acid.

The next step of the processes involves the removing of the insolublematerial from the slurry formed by the reaction of the aqueous alkalinesolution with the uric acid enriched raw material, i.e., that rawmaterial which has passed through the desired sieve. Any liquid/solidseparation technique can be utilized in order to carry out thisoperation. For example, such engineering techniques as decantation,filtration and centrifuging can be utilized. In carrying out theprocesses of the present invention on a commercial scale, it is foundthat the preferred removal technique is centrifuging.

Immediately prior to the step of removal of insoluble material from theslurry, it is sometimes desirable to age the slurry formed in thepreceding step, preferably by stirring the slurry for a sufiicientperiod of time to insure complete dissolution of the uric acid containedin the raw material. Preferably this aging takes place over a period offrom about one minute to about sixty minutes; however, where the time isnot critical, the aging can be for any period, for example 24 hours orlonger.

In the next step, a flocculating agent is contacted with the solutionobtained from the first slurry in order to form a second slurrycontaining additional insoluble material. Preferably the contacting ofthe flocculating agent with the first fluid is carried out with at leastintermittent agitation or stirring in order to insure substantiallycomplete contacting with the flocculating agent. The flocculating agentcan be any typical and commonly known flocculating agent which does notadversely afliect the desired end result. For example, the followingflocculating agents can be utilized in the present invention: alkalineearth metals (such as calcium, magnesium and barium), zinc, iron, andaluminum hydroxides, oxides, halides, and acetates and mixtures thereof.The preferred flocculating agent is calcium chloride.

The amount of the flocculating agent employed in the processes of thepresent invention and particularly in this step thereof is generally inthe range of from about 0.01% to about 20%, preferably from about 2% toabout 15% by weight based on the total weight of the uric acid enrichedraw material being treated. It is thought that the flocculating agent,such as calcium chloride, reacts with any of the lignins remaining inthe fluid to form additional insoluble material and which thus resultsin the formation of a second slurry.

Subsequent to the flocculating step and if one so desires, the secondslurry formed by the addition of the flocculating agent can be aged withor without stirring in the manner heretofore described in conjunctionwith the formation of the first slurry.

In the following step, the additional insoluble material formed due tothe addition of the flocculating agent in the above step is removed fromthe liquid in the second slurry by the same techniques heretoforedescribed. As previously mentioned if one so desires to age the firstslurry without stirring and thus permit sedimentation of some of thesolid materials therein, the first insoluble material produced need notphysically be removed from the overall mixture but may be removed alongwith the additional insoluble material formed by the reaction of theflocculating agent with the lignins. With the removal of all theinsoluble material from the second slurry, there is then formed a secondfluid.

In the next step, the above described second fluid is reacted with asuflicient amount of an acidic material to form a precipitate from thissecond fluid. It is to be understood that the term acidic material isany material which, when added to the second fluid, will lower the pH toless than about 6.0 and cause the dissolved uric acid therein toprecipitate out of solution. It is preferred that the acidic material bean aqueous solution of a mineral acid. Almost any mineral acid may beemployed in the aqueous solution of a mineral acid used in this step inorder to precipitate the uric acid from the solution.

Hydrochloric and sulfuric acids are preferred, and sulfuric acid isparticularly preferred. The preferred sulfuric acid solutions, utilizedfor this purpose, have a H 80 concentration of from about 30% to about95 by weight, based on the total weight of the aqueous solutioncontaining said mineral acid.

The amount of acidic material employed is that amount which will resultin the second fluid having a pH of less than about 6.0 and therebyprecipitating the uric acid. The preferred amount utilized is such thatthe end pH of the second fluid is less than about 5, preferably fromabout pH 1 to about pH 4.5, and more preferably less than 4 (forexample, from about pH 3 to about pH 3.5).

After precipitation of the uric acid, and if one so desires, theprecipitate containing second fluid can be aged, with or withoutstirring, for a suflicient period of time in order to optimize theprecipitation of the uric acid.

The precipitate is then removed from the second fluid in a similarmanner as the insoluble material is removed from the slurries aspreviously described.

The precipitate which is recovered from the second fluid is then reactedwith a suflicient amount of an alkaline solution to dissolvesubstantially all of the precipitate therein to form a third fluid. Theaqueous alkaline solution utilized is the same as that heretoforedescribed; however, the amount thereof utilized will be somewhat lessthan heretofore mentioned, since the amounts and volumes of materials atthis point are less than the initial amounts handled in the initialsteps of this process.

The uric solution is again precipitated with an acid solution. Thisprecipitate is the substantially pure uric acid which is present inyields of at least about 85% and generally from about 90% to about 95%by weight based on the weight of the total uric acid contained in theminus fraction, i.e., the initially treated raw material which haspassed through the desired sieve. The amount of acidic material utilizedis any amount which will provide a pH of less than about 6 and alsopromote the formation of the substantially pure uric acid precipitate.

The precipitated uric acid or uric salt is washed with an aqueoussolution. The water-washed uric acid material is then washed with aninert liquid, non-aqueous organic solvent to remove residual water.Generally alcohols, ethers and ketones are suitable and may be employedas long as the organic liquid is substantially inert to the uric acidand that the uric acid is substantially insoluble in the organic liquid.

The substantially pure uric acid which has been washed with water,followed by an organic solvent wash, may then be dried at a temperatureof less than about 480 R, which is the decomposition point of uric acid,preferably at a temperature of from about 80 F. to about 480 F., andmore preferably from about 100 F. to about 300 F. The drying timeusually is from a period of about thirty minutes to about six hours.

The resultant product is a substantially pure, waterfree, free flowinguric acid. It is significant to note at this point that the uric acid issubstantially pure and of a chemical grade type uric acid which isreadily adaptable to be utilized for pharmaceutical purposes.

If the uric acid after the last dissolution in the alkaline solution isnot substantially colorless or white, it may be further treated to makeit substantially colorless. The last alkaline solution containing thedissolved uric acid is heated to a temperature of from 70 F. to about200 F. It is then passed through carbon-containing material to removethe color producing impurities. The carbon may be mixed with thesolution or the solution may be passed through a carbon column. If thecarbon is mixed in, this then must be removed with the color causingimpurities trapped therein.

The activated carbon is the type commercially available under thetrademark Darco S51 Activated Carbon. One of the physical properties ofthis activated carbon is its total surface, which is directlyproportional to the absorption capacity. It should also be noted thatthe utilization of activated carbon does not produce or result in anysignificant pH changes in the uric acid con taining solution beingtreated. While porous, activated carbon was utilized in the examples ofthe present invention, other types or forms of carbon, i.e., carbonblack, lampblack, boneblack, etc., which have absorption characteristicssimilar thereto may be used. It is preferred to use an activated carbonhaving a surface area of fromabout 200 to about 1,500 square meters pergram. Either the batchwise process or the continuous process of treatingthe uric acid containing solution with carbon are satisfactory.

The amount of carbon containing material, preferably activated carbon,which is added to the uric acid containing solution is preferably withinthe range of from about 0.000l% to about 40%, more preferably from about0.01% to about by weight (dry basis) of the total uric acid in the uricacid containing solution. However, it is within the scope of the presentinvention that any amount of carbon can be utilized as long as thedesired end results are achieved.

If the subsequent separation or removal of the carbon from the uric acidcontaining solution is to be effected or carried out by filtration whena batchwise process is utilized, a filtering aid such as Dicalite 4200diatomaceous earth may be added. The amount of a filter aid which isadded to the carbon-containing third fluid may be any amount which iseffective to achieve the desired end result and is preferably from about0.001% to about 60%, more preferably from about 0.1% to about by weightof the total uric acid in solution.

After the addition of the carbon and the filter aid into the vesselcontaining the uric solution, the resultant solution is then agitatedfor a period of time from about five minutes to about thirty minutes, inorder to achieve an adequate dispersion of the carbon and filter aidtherein. Subsequently the carbon and filter aid are removed and the uricsolution is then processed as theretofore described.

As was previously mentioned, the aqueous alkaline solution should beadjusted to a pH of at least 6.5 to dissolve the uric acid. Thesolubility characteristics, however, of uric acid and primary saltsthereof in various pH solutions allow for a procedure to obtain asubstantially pure primary salt of uric acid. Thus, if the aqueoussolution is sodium hydroxide, the monosodium urate may be obtained byproper adjustment of the pH. If the aqueous solution is potassiumhydroxide, then, of course, the compound precipitated will be monopo--tassium urate. The primary salts have different solubilitycharacteristics than the uric acid itself and are, therefore, sometimesmore desirable.

If one, therefore, dissolves the uric acid in a very highly alkalinesodium hydroxide solution with a pH of greater than 11, the uric acidwill be completely dissolved as the disodium salt. If the pH iscontinually decreased, the primary salt or monosodium salt of uric acidis formed. Thus, primary salts of uric acid may be obtained having anempirical formula of: MHC H N O M in the empirical formula is a saltfrom the group consisting of alkaline earth metals. Uric acid itself hasa pK of 5.7 (Bergman, F. and Dickstein, S., Jour. of Am. Chem. 80., 77,691 [1955]). Thus, at a solution pH of 6.7, 90% of the uric acid will bein the form of monosodium urate with 10% existing as uric acid. At a pHof 5.7, the mixture will be approximately of the primary salt and 50% ofthe uric acid. At a pH of 4.7 the mixture will be essentially 10% in theform of the primary salt and in the form of uric acid. One can utilizethe solubility characteristics of the salts to make it possible by useof the process described herein to precipitate out substantially pureprimary salt of uric acid or as substantial- 1y pure uric acid itselfdepending on the pH adjustment.

In the case of sodium hydroxide solution, if the pH is adjusted to apreferred pH of 7.8, substantially pure monosodium urate may beprecipitated out, however, a broad range of from pH 6.5 to pH 8.5 issatisfactory. If one wishes to obtain uric acid, the pH should be below5.5 with a more preferred range below pH 4.5 and an ideal pH of 3.5.

As mentioned heretofore, these processes of the present invention can becarried out on a continuous basis instead of a batchwise process.Illustrative of such a process would be the continuous collecting anddrying of a suitable raw material, such as wet chicken manure. The driedraw material can be continuously milled and the milled product can bescreened on a rotating or moving conveyor which contains a screen (suchas a No. 8 mesh U.S. Standard screen) to produce a product having twofractions, the minus-fraction and a plus-fraction. The minus-fraction ofthe dried raw material can then be fed, along with an aqueous alkalinesolution, into a reaction vessel which is equipped with a mechanicalagitator and a baffle plate extending in an angular manner across aportion of the top part thereof. A slurry is formed in the top sectionof said vessel and settles to the bottom of the vessel, whereby theslurry is removed via a screw conveyor. The slurry can then becontinuously fed to a centrifuge which removes both the solids and theliquid therefrom, with the liquid being fed into a second reactionvessel which is of similar construction to the first reaction vessel.The resultant slurry is removed from the second vessel in the samemanner, fed through a centri- :fuge, and the fluid injected into a thirdreaction vessel along with sulfuric acid, to form a precipitate. As theprecipitate settles to the bottom and collects, it is removed therefromby a screw conveyor. The precipitate, which is removed from the thirdvessel, is then fed into a centrifuge and the precipitate, which is thecrude uric acid, is then redissolved in a fourth reaction vessel whichcontains an aqueous alkaline solution. In this fourth vessel, however,the aqueous alkaline solution and precipitate are fed into the bottomportion of the vessel and the resultant solution merely allowed to flowover the top and collected and conveyed to a fifth vessel. In this fifthvessel, the result-ant solution from the fourth vessel is admixed withacidic material such as sulfuric acid to form the final uric acidprecipitate which is removed from the vessel by a screw conveyor locatedat the bottom thereof and extending into said vessel. Subsequently, theprecipitate-containing solution is subjected to centrifuging in a mannerheretofore described.

A further understanding of the processes and composi- -t-ions of thisinvention will be obtained from the following specific examples whichare intended to illustrate the invention but not to limit the scopethereof, parts and percentages being by weight unless otherwisespecified.

EXAMPLE 4 Chicken waste which was collected within a 24-hour period ofits production was dried at a temperature of 300 F. Subsequent to thedrying, the material was passed through a hammer mill and sieved over an80 mesh screen. One hundred pounds of the less than 80 mesh material wasthen passed into an extraction tank containing 375 gallons of water, 15pounds of sodium hydroxide, and 30 pounds of sodium chloride. The pH ofthis extraction solution was adjusted to 11.3. The mixture was agitatedfor 30 minutes and centrifuged. To the effluent from the centrifuge,which was approximately 360 gallons, was added 9 pounds of calciumchloride. The calcium chloride precipitated most of the lignincontaminants. This mixture was centrifuged and the filtrate heated to180 F. and passed through a carbon column. The carbon column was packedwith 30 pounds of activated carbon commercially available fromPittsburgh Carbon Designated Granular 451. The effluent from the carboncolumn was acidified to a pH of 3.5 using sulfuric acid. The uric acidprecipitate was collected by centrifugation and washed with 5 gallons ofwater. The final product was finally washed with 3 gallons of methanoland dried. The uric acid was obtained and analyzed to be 98.2% pureuric, approximately 9.8 pounds of uric acid was obtained, which waslight tan in color.

EXAMPLE 5 Chicken waste was treated in the same manner as Example 4except that calcium chloride dihydrate was substituted as theflocculating agent instead of calcium then centrifuged and thencontinued as Example 4. chloride. The mixture was stirred for 30 minutesand 9.2 pounds of uric acid analyzing to 99.3% purity was obtained.

EXAMPLE 6 Chicken waste of less than mesh and of pounds dry weight wasobtained by drying and sieving as in the previous examples. This wasplaced in an extraction tank containing 375 gallons of water, 15 poundsof sodium hydroxide, and 30 pounds of sodium chloride. The pH of thesolution was 11.3. The mixture was agitated for 30 minutes andcentrifuged. To the effluent of approximately 360 gallons, was added 9pounds of calcium chloride dihydrate. This mixture was stirred for 30minutes and centrifuged. The efiluent from the centrifuge was acidifiedto a pH of 3.5 with sulfuric acid. The precipitated uric acid wasseparated by centrifugation. The precipitate was slurried and washed in15 gallons of a 4% by weight sodium phosphate dodecahydrate solution.

Basic wash is carried out using 0.05% to 8% of an aqueous solution of analkali metal hydroxide or phosphate. The ammonium salts of these anionscan also be used. At any rate, the wash removed alkaline solubleimpurities and most of the colored impurities from the uric acidprecipitate. Regardless of the method used, the uric acid precipitate isdissolved in 30 gallons of 8% aqueous sodium hydroxide solution at 150F. and passed through a carbon column containing 30 pounds of activatedcarbon. The effluent was acidified to a pH of 3.6 and the uric acidproduct isolated by centrifugation. The product was washed with 5gallons of water and 3 gallons of methanol; 9.3 pounds of dry productwhich is white 111 color was analyzed to be 99.6% pure.

EXAMPLE 7 The procedure given in Example 5 was followed except thatafter the slurrying, the chicken waste in the extractron tank with 375gallons of water, 15 pounds of sodium hydroxide, and 30 pounds of sodiumchloride, 9 pounds of calcium dichloride dihydrate were added and thesolution stirred for 15 minutes. The mixture was centrifuged and theprocess continued following the extraction procedure after the additionof calcium chloride. 9.3 pounds of a white product were obtained andanalyzed to be 99.5% pure uric acid.

As was stated, a continuous extraction process has also been developedutilizing the same basic techniques but providing for a continuous flowof materials. The method utilizes dried, ground and separated wastematerial for the starting material and provides process given maximumextraction efficiency and minimum impurities to obtain chemically pureand biologically acceptable uric acid. The continuous process has threemajor operations: (1) grinding and sieving, (2) extraction, and (3)purification.

The continuous process can best be shown by Example 8 which follows:

EXAMPLE 8 Four thousand pounds of waste material was collected andprocessed within 2-4 hours. The material was dried in a flash drier at atemperature of F. to 390 F.

In this specific eXample, a temperature of 350 F. was used.

The drying operation reduced the material to a weight of 1,000 pounds ofdried Waste material. The 1,000 pounds of dried waste material was fedinto a hammer mill through which the material is passed over in the 80mesh screen. The size fraction of less than 80' mesh fraction wascollected and amounts to 470 pounds of material.

Subsequent to this grinding and drying operation, a continuousextraction process is utilized, utilizing 800 pounds per hour of 80 meshmateral which was conveyed continuously into a 1,000 gallon tank.Simultaneous to conveying the dried material to the mixing tank, therewas also added 1,440 gallons per hour of water and 150 gallons per hourof 0.1% sodium chloride and 0.5% sodium hydroxide, giving a pH of 11.5.The waste material is retained in the tank for about 30* minutes at thismixing rate.

The material was thoroughly mixed and the extracted liquid results in adark colored slurried, dissolved disodium urate. The slurry was pumpedat a rate of 1,440 gallons per hour to a continuous operational scrolltype centrifuge. The dissolved disodium urate was extracted from thesludge material.

The 1,440 gallons per hour of the disodium urate solution was directedto an acidification tank where the liquor was acidified withconcentrated sulfuric acid to the acidification tank. A light tanprecipitate was formed which is crude uric acid analyzing to about 80%purity. If a 300-gallon acidification tank was used, the retention timefor contact with sulfuric acid is about 10 minutes. Continuing with thecontinuous operation, the slurry from the acidification tank was pumpedat a rate of 1,440 gallons per hour to a second centrifuge, preferably,a basket type centrifuge. Crude uric acid precipitate was collected andseparated from the acidic mother liquor at the rate of 87.5 pounds perhour.

The process was continued by collecting 700 pounds of the crudeextracted uric acid and fed into an 8,000 gallon mixing tank, to whichwas added 500 pounds of sodium hydroxide, 300 pounds of a filter aidsuch as Celite, which is a mixture of diatomaceous earth and clay and5,820 gallons of water, which has been preheated to 170 F. The pure uricacid was once again dissolved but the ligneous impurity remained out ofthe solution. The dissolved heated disodium urate was pumped from themixing vessel at a rate of 730 gallons per hour directly through apositive pressure filter. A clear disodium urate solution ofapproximately 94% to 96% purity was obtained as an eflluent from thefilter and was directed through an activated carbon column to remove anyremaining dissolved coloring impurities.

The 170 F. effluent was pumped from the carbon column at the same rateof 730 gallons per hour into a ZOO-gallon acidification tank. To thistank was added concentrated sulfuric acid at a rate of 7 gallons perhour which results in a solution having a pH of 3.0 and retention timeof about 10 minutes. Pure uric acid was precipitated out of thesolution. The solution containing the slurry of precipitated uric acidwas passed through a centrifuge which collects solid uric acid having ananalyzed purity of 99.5%. The pure uric acid crystals may be furthercleansed and purified to a final analysis of about 99.8% by washing thecrystals with a water and methanol wash. After the wash, theprecipitated and washed uric acid was dried in an oven to obtain thepure product.

EXAMPLE 9 Example 8 above is repeated except that prior to the finalacidification step, there Was charged together with the filter aid, 250pounds of Darco activated carbon. The slurry was then acidified anddried according to Example 8. The end product had a purity of 98.3% uricacid with an extremely white coloration to the product.

The procedure according to Examples 8 and 9' has been conducted usinghydrochloric acid instead of sulfuric acid as the acidifying agent.Essentially the same results were obtained with hydrochloric acid.Phosphoric acid will also give the same results.

The procedure according to Example 8 has also been conducted except thatpotassium hydroxide, lithium hydroxide and sodium carbonate are usedinstead of sodium hydroxide as the alkaline material in solution todissolve the uric acid with substantially identical results. Economicfactors will govern the choice of caustic material with sodium hydroxidebeing the preferred caustic at the present state of relative costfactors.

It is also within the scope of the present invention that, as analternative to the use of the carbon treatment to remove color-causingimpurities, immediately prior to the final drying step, the precipitatecan be washed with a dilute aqueous solution of an alkali metal andammonium hydroxides and alkali metal phosphates, e.g., sodium phosphateor sodium hydroxide. It is desirable that the concentration of saidsolution be less than about 0.1 Normal. Furthermore, the temperature ofthe solution must be less than about 25 C. These conditions arenecessary in order to prevent the uric acid from being dissolved in saidsolution.

EXAMPLE 10* Example 8 is repeated in the same manner as described abovewith the sole exception that turkey manure is used as the starting rawmaterial instead of chicken manure. The uric acid content in the turkeymanure is found to be similar to that in the chicken manure.Substantially the same results are obtained in this Example 10- as thoseresults obtained in Example 8.

In conjunction with the foregoing examples of the pres ent invention,Examples 1 and 2 of United States Letters Patent Number 2,302,204 arerepeated in the exact manner as described in this publication in orderto obtain comparative yield data between the present invention processesand the processes of United States Letters Patent Number 2,302,204. Inthis repeat it is found that the uric acid yields, based on the totaluric acid content of the actual material being treated, are 56% and 61%by weight, respectively, for Examples 1 and 2. These results arecontrasted to the yields found in the above present invention examples,i.e., %95% by weight. Thus, the present invention advantages are quitevividly illustrated. As mentioned heretofore, one of the importantfeatures of the present invention is the preparation of uric acid inhigh yields and which has been unobtainable in practicing the prior artprocesses.

Examples 11 and 12 are indicative of the effectiveness of this processfor obtaining primary salts of uric acid by proper adjustment of pH.This was previously explained. Examples 11 and 12 show how effectivethis procedure can be.

EXAMPLE 11 The same procedure was followed as in Example 4 except thatthe effluent from the carbon column was acidified to a pH of 7.5 usingsulfuric acid. The mono sodium urate precipitate was allowed to settleover night. The final product of precipitate collected was washed withmethanol and dried. The precipitate was analyzed to be 98.5% monosodiumurate.

EXAMPLE 12 The same procedure was used as in Example 4 except that theextraction tank contained 15 pounds of potassium hydroxide and 30 poundsof potassium chloride. The procedure was continued as shown except thatthe efiluent from the carbon column was acidified to a pH of 7.7 usingsulfuric acid. Monopotassium urate was collected as the precipitate,washed and dried and analyzed to be 97.9% monopotassium urate.

While the particular embodiments of the present invention have beenshown and described specifically in the examples heretofore set forth,it will be obvious to those skilled in the art that changes andmodifications may be made without departing from this invention in itsbroader aspects.

What is claimed is:

1. The method of obtaining uric acid from a waste ma terial containinguric acid comprising the steps of:

collecting suitable uric acid bearing waste material promptly after ithas been produced; drying said promptly collected waste material withina period of eight days after it has been produced at a temperature offrom between 140 F. to 390 F. for a period of time until the moisturecontent is reduced to no more than 15% weight of water;

milling and collecting a fraction of at least -80 mesh of the milled anddried waste material; extracting said fraction material a first timewith an alkaline-brine solution having a pH of greater than 9;

acidifying the mother liquor of said first extracted material with anacid in a solution having a pH of from 1 to 5.5;

extracting the precipitated material from the acidified solution asecond time by dissolving said precipitate in an alkaline-brine solutionhaving a pH of greater than 9; and

acidifying said second extracted material to a pH of from 1 to 5.5thereby precipitating the pure uric acid so produced from thesupernatant liquid. 2. A method of obtaining uric acid from a wastematerial containing uric acid according to Claim 1 comprising anadditional step of treating said first extracted solution with afiltering aid indirectly to remove impurities.

3. A method of obtaining uric acid from a waste material containing uricacid according to Claim 1 comprising the additional step of furtherpurifying and decolorizing said solution of uric acid which has beenextracted a second time by intimately treating said solution with anactivated decolorizing carbon.

4. A method of obtaining uric acid from a waste mate rial containinguric acid according to Claim 3 in which the solution is treated withactivated carbon in which the treatment comprises passing said solutionthrough a carbon column of activated decolorizing carbon.

5. A method of obtaining uric acid from a waste material containing uricacid comprising the steps of:

collecting suitable waste material which has been produced within theeight days prior to said collection;

drying said freshly collected waste material at a temperature of from140 F. to 390 F. for a period of time sutficient to reduce moisturecontent to no greater than 15% weight of Water;

grinding and collecting the fraction of the ground material of at least80 mesh;

extracting said collected material with an alkaline-brine solution;

contacting said extracted fraction with a flocculating material tosettle out any lignin material present; acidifying the supernatantliquid of the extracted fraction of a pH of from 1 to 5.5; and

collecting the precipitated material to obtain a uric acid of from 80%to 95% purity.

6. The process according to Claim comprising the additional steps ofpurifying said uric acid by:

dissolving the uric acid in an alkaline-brine solution having from 5% to10% alkaline concentration; passing the liquid from the fiocculantthrough an activated decolorizing carbon column; and

precipitating out the uric acid from the effluent from the carbon columnby acidifying the efiluent to a pH of from 1 to 5.5.

7. The process according to Claim 5 in which the flocculating materialis calcium chloride.

8. A process according to Claim 6 comprising the additional steps ofpurifying the uric acid by first washing with water and then a methanolsolution and then drying said washed uric acid.

9. A process according to Claim 5 in which the said collected materialis extracted with an alkaline-brine solution having a pH of greater than9.

10. A method of obtaining a primary salt of uric acid from a wastematerial containing uric acid comprising the steps of:

collecting suitable waste material which has been produced within theeight days prior to said collection;

drying said freshly collected waste material at a temperature of from140 F. to 390 F. for a period of time until the moisture content is nomore than 15% weight of water;

grinding and collecting the fraction of the ground material of at leastmesh;

extracting said collected material with an alkaline-brine solution;

contacting said extracted fraction with a flocculating material tosettle out any lignin material present; passing the liquid from theflocculant through an activated decolorizing carbon column; and

precipitating out the primary salt of uric acid from the efiluent fromthe carbon column by adjusting the pH of the efiiuent with an acidsolution of a pH of from 5.5 to 9. 11. The process according to claim 10in which the preferred pH is of from 6.5 to 8.5.

12. The process according to Claim 11 in which the preferred pH issubstantially 7.8.

13. A process according to Claim 10 in which the extraction with thealkaline-brine solution comprises an alkaline compound which is asolution of an alkali metal hydroxide in an aqueous solution.

14. A process according to Claim 10 in which the alkali metal hydroxideis selected from the group consisting of sodium hydroxide, lithiumhydroxide, potassium hydroxide and ammonium hydroxide.

15. The method of obtaining monosodium urate according to Claim 10 inwhich the alkaline-brine solution is an aqueous solution of sodiumhydroxide.

16. A process for preparing substantially pure uric acid from a wastematerial containing uric acid comprising the steps of:

drying promptly a freshly collected suitable raw material producedwithin the eight days prior to said drying and containing uric acid fora period of time and at a sufiicient temperature to substantiallyterminate biological degradation of said raw material to form a materialhaving a stabilized uric acid content;

collecting a fraction of said stabilized uric acid containing material,said fraction containing a major portion of said stabilized uric acid;

extracting said fraction with an amount of alkaline material capable ofdissolving substantially all of the stabilized uric acid;

contacting said extracted material with a fiocculating agent to formadditional insoluble impurities therein; and

acidifying the mother liquid of said extracted material with asufiicient amount of acidic material to precipitate the uric acidtherein.

17. A process for preparing substantially pure uric acid from a Wastematerial containing uric acid according to Claim 16 in which there isincluded the additional steps of:

subsequently again extracting the precipitated uric acid to dissolvesubstantially all of the precipitate; and acidifying the extractedsolution to form a precipitate which is substantially pure uric acid.

18. A process according to Claim 16 in which the process is carried outin batch operations.

'19 19. A process for preparing substantially pure uric acid from awaste material containing uric acid according to Claim 18 including theadditional steps prior to the step of acidifying the extracted solutionto form the precip1- tate of:

heating and maintaining said extracted solution at a temperature of fromabout 70 F. to about 210 F.;

contacting said heated solution with a suflicient amount of activatedcarbon material for a sufficient period of time to remove colorizingimpurities from said solution; and

subsequently removing said carbon material from said extracted solution.

20. A process for preparing substantially pure uric acid from a wastematerial containing uric acid according to Claim 19 including theadditional steps subsequent thereto of:

washing the substantially pure uric acid precipitate with an organicmaterial to remove free water therefrom; and

drying said Washed precipitate at a sufficient temperature and for asufficient period of time to form a substantially pure, free flowinguric acid.

21. A process as set forth in Claim 20 in which the organic solvent washof the pure uric acid precipitate is selected from the group consistingof methanol, propanol, ethanol or mixtures thereof to remove water fromthe precipitate.

22. A process for preparing substantially pure uric acid from a wastematerial containing uric acid according to Claim 16 in which the Wastematerial containing uric acid is a fowl waste material from the groupconsisting of chicken manure and turkey manure.

23. A process for preparing substantially pure uric acid from a wastematerial containing uric acid comprising the steps of:

collecting suitable uric acid bearing waste material promptly after ithas been produced;

drying said promptly collected waste material within a period of eightdays after it has been produced for a period of time and at a suflicienttemperature to substantially terminate biological degradation of saidraw material to form a material having a stabilized uric acid content;

grinding said stabilized waste material;

collecting a fraction of said ground, stabilized uric acid containingmaterial, said fraction containing a major portion of said stabilizeduric acid;

extracting said collected fraction a first time with an amount ofalkaline solution which is capable of dissolving substantially all ofthe stabilized uric acid;

contacting the supernatant liquid obtained from the first reaction witha sufiicient amount of fiocculating material to form insolubleimpurities;

acidifying the supernatant material obtained from the flocculating stepwith sufiicient amount of the acidic material to precipitate uric acidcontained therein;

extracting a second time said precipitate with a sufiicient amount ofaqueous alkaline solution to dissolve substantially all of theprecipitate;

heating and maintaining said second extracted material at a temperatureof from about 70 F. to 210 F.;

contacting said heated material with a sufiicient amount of activatedcarbon material for a sufficient amount 20 of time to remove colorcausing impurities therefrom;

acidifying a second time the decolorized mother liquor with a sufficientamount of acidic material to form a substantially pure precipitate ofuric acid;

washing the substantially pure uric acid precipitate with an organicsolvent to remove free water therefrom; and

drying said washed precipitate at a sufficient temperature to form asubstantially pure, water free uric acid.

24. The process according to Claim 23 wherein:

a suitable uric acid containing raw material is selected from the groupconsisting of chicken manure and turkey manure;

the alkaline extraction solution is selected from the group consistingof sodium hydroxide, lithium hydroxide, potassium hydroxide, ammoniumhydroxide solutions and solutions of mixtures thereof; and

the acidifying material is a solution of a mineral acid from the groupconsisting of sulfuric acid, hydrochloric acid and mixtures thereof.

25. A process according to Claim 23 wherein an alkaline-brine solutionis used as the extracting solution wherein the brine is formed from anelectrolyte selected from the group consisting of alkali metal, alkalineearth metal, alkali halides, ammonium halides and nitrates, sulfates andcarbonates of alkali metals, said electrolyte utilized in at least oneof the aqueous alkaline extracting solutions.

26. A process according to Claim 25 wherein the electrolyte is sodiumchloride.

27. A process according to Claim 23 wherein at least one of the alkalineaqueous solutions comprises sodium hydroxide and sodium chloride and theacidifying solution is sulfuric acid.

28. A process according to Claim 23 wherein the collected fraction iscollected from ground material which is characterized by having anaverage particle size of about less than 2,000 microns and passingthrough a No.

mesh US. Standard screen.

29. A process according to Claim 23 in which the flocculating agent iscalcium chloride.

30. A process according to Claim 23 in which the process is carried outin a continuous operation.

31. A process according to Claim 27 in which the alkaline extractingsolution contains:

from about 2 to about 20% by weight of fraction of sodium hydroxide;from about 0.01 to about 50% by weight based on the total weight of thefraction of sodium chloride; and water present in a ratio of Water tosaid fraction of from about 10:1 to 50:1.

References Cited UNITED STATES PATENTS 2,302,204 1l/l942 Gable et al.260255 ALEX MAZEL, Primary Examiner A. M. T. TIGHE, Assistant ExaminerUS. Cl. X.R. 99'-2,

1. THE METHOD OF OBTAINING URIC ACID FROM A WASTE MATERIAL CONTAININGURIC ACID COMPRISING THE STEPS OF: COLLECTING SUITABLE URIC ACID BEARINGWASTE MATERIAL PROMPTLY AFTER IT HAS BEEN PRODUCED; DRYING SAID PROMPTLYCOLLECTED WASTE MATERIAL WITHIN A PERIOD OF EIGHT DAYS AFTER IT HAS BEENPRODUCED AT A TEMPERATURE OF FROM BETWEEN 140*F. TO 390*F. FOR A PERIODOF TIME UNTIL THE MOISTURE CONTENT IS REDUCED TO NO MORE THAN 15% WEIGHTOF WATER; MILLING AND COLLECTING A FRACTION OF AT LEAST -80 MESH OF THEMILLED AND DRIED WASTE MATERIAL; EXTRACTING SAID FRACTION MATERIAL AFIRST TIME WITH AN ALKALINE-BRINE SOLUTION HAVING A PH OF GREATER THAN9; ACIDIFYING THE MOTHER LIQUOR OF SAID FIRST EXTRACTED MATERIAL WITH ANACID IN A SOLUTION HAVING A PH OF FROM 1 TO 5.5; EXTRACTING THEPRECIPITATED MATERIAL FROM THE ACIDIFIED SOLUTION A SECOND TIME BYDISSOLVING SAID PRECIPITATE IN AN ALKALINE-BRINE SOLUTION HAVING A PH OFGREATER THE 9; AND ACIDIFYING SAID SECOND EXTRACTED MATERIAL TO A PH OFFROM 1 TO 5.5 THEREBY PRECIPITATING THE PURE URIC ACID SO PRODUCED FROMTHE SUPERNATANT LIQUID.